1. Field of the Invention
The present invention relates to an ink jet printing head for ejecting liquids like ink and an ink jet printing apparatus which carries out a printing operation using the printing head. Apart from a general printing apparatus, a copying machine, a facsimile machine with a telecommunication system, a word processor and the like with a printing unit, or a multifunction printing apparatus combining these apparatuses can be adopted as a form of the ink jet printing apparatus.
2. Description of the Related Art
The ink jet printing apparatus is a printing apparatus adopting a so-called non-impact printing method, and is characterized by its capability of high speed printing, capability of printing on various print media, little noise generation at the time of printing, and the like. For this reason, the ink jet printing apparatus is widely adopted as an apparatus for undertaking printing operations in printers, copying machines, facsimile machines, word processors and the like.
Typical ink ejection methods in printing heads mounted on the ink jet printing apparatus include the one using electromechanical transducers like piezo elements and the one ejecting ink droplets due to an effect of heat generated by an irradiation of electromagnetic waves like lasers. However, those ejecting ink droplets due to an effect of film boiling by heating ink with electrothermal transducer elements having heat elements are widely used. In the ink jet printing heads of this form, the electrothermal transducer elements are provided in an inner side of an ink ejection opening and electric pulses, which become print signals, are supplied thereto to generate heat. Thermal energy is given to ink by this and by using bubble pressure at the time of ink foaming (at the time of boiling) generated by a phase change of ink at the time, printing to a printing medium is carried out by ejecting microdroplets of ink from a minute ejection opening. The ink jet printing head generally has a nozzle for ejecting ink as a droplet for example, and an ink supplying system for supplying ink to this nozzle.
The printing apparatus with the ink jet printing head as described above is capable of outputting letters and images of high quality with low cost. The ink jet printing apparatus using a principle, in which the film boiling is generated in liquid and ink is ejected accompanied with bubble formation (generation, development, defoaming, and extinction), is particularly the mainstream of the ink jet printing apparatus. This is because such printing apparatuses have an advantage in that they are capable of carrying out color printing at low cost by using ink jet printing heads having an ejecting portion for ejecting color liquids such as cyan, magenta, and yellow inks, apart from a black ink as a black liquid.
Under a condition where higher speed and definition of printing are demanded, generally 64, 128, and even 256 or more of the ejection openings are now being provided in the ejecting portion in the ink jet printing head. Moreover, an arrangement density of the ejection opening is becoming 300 dpi, 600 dpi or more, where a notation “dpi” describes a number of the ejection openings per one inch, and is also being enhanced. The heat element as an electrothermal transducer arranged in the respective ones of these ejection openings forms bubbles due to film boiling by pulse drives in the order of a few μsec to 10 μsec, realizing high speed printing with high image quality by such a high frequency drive.
As one form of such an ink jet printing apparatus, the one using an ink jet printing head with an ejecting portion or an ink jet printing head integrating the ejecting portion and an ink container as a cartridge is available. In other words, this is a configuration (for example, Japanese Patent Application Laid-open No. 2001-322279) where the cartridge is attachable/detachable to/from a support unit (a carriage for mounting the printing head and making it scan printing media in a predetermined direction in a serial type printing apparatus) provided in the main body of the printing apparatus. A power supply wiring terminal and a ground wiring terminal both for applying power to the electrothermal transducer elements, and data terminal and the like for receiving and transmitting data for drive controlling the electrothermal transducer elements in response to printing data and the like, are provided in an ink jet printing head side and a printing apparatus side. These terminals contact with each other to electrically connect the ink jet printing head and the printing apparatus when the ink jet printing head is mounted.
However, when the ink jet printing head is not mounted in a normal position in the main body of the printing apparatus, contact of the terminals of the printing head with the terminals of the main body of the printing apparatus become insufficient and a normal drive of the ink jet printing head is not carried out. Moreover, in extreme cases, by inputting unexpected electric pulses to the printing head, there is a concern that an element substrate provided with the electrothermal transducer elements of the ink jet printing head and the like is being destructed.
Accordingly, detection of normal mounting before the electrical connection for carrying out printing operation is strongly desired. It can be considered to apply the one disclosed in Japanese Patent Application Laid-open No. 11-099679 (1999) as a configuration for carrying out such detection although it is not directly related to the ink jet printing apparatus. The configuration detects whether each of signal lines from a control substrate is inserted or not by calculating logical product between a heating control line and respective plural data lines, in print head for printing using a thermal transfer ribbon and the like.
However, the number of terminals for carrying out the electric connection described above also increases when multiple ejection openings are implemented with high density in the ejecting portion and furthermore, when use of an ink jet printing head provided with a plurality of ejecting portions corresponding to plural colors of ink are becoming mainstream. Therefore, an application of a technique disclosed in Japanese Patent Application Laid-open No. 11-099679 (1999) to detect the presence or absence of contacts of all terminals leads to a longer detection time. Moreover, since the number of wirings for a detection mechanism increases, there are problems in that upsizing of a substrate for mounting various elements and a printing head takes place and manufacturing cost increases.